1. Field of the Invention
This invention relates to a signal processing circuit for a solid state imaging apparatus in which an imaging output signal from a solid-state image sensor for generating image signals is digitized and a detail signal for performing image enhancement is formed by digital signal processing. More particularly, the present invention relates to a signal processing circuit for a solid state imaging apparatus in which spatial pixel shifting or offsetting is performed by the imaging section, that is, the solid state image sensors for green and red color imaging are arranged with a spatial offset of one half the pixel repetition pitch.
2. Description of the Prior Art
In a solid state imaging apparatus in which the imaging section includes a solid-state image sensor having a discrete pixel structure which is formed by charge coupled devices (CCDs), since the solid state image sensor is a sampling system, aliasing components from the spatial sampling frequency fs are mixed into imaging output signals from the solid state image sensor as, for example, shown by the hatched line in FIG. 1.
Typically, to prevent aliasing components from being mixed into the baseband of the imaging signals, the high frequency side of the baseband components of the imaging signal is suppressed so as to satisfy the Nyquist conditions of the sampling system by the solid state image sensor.
A color television camera may include a multi-CCD type solid-state imaging apparatus, such as a two CCD type imaging apparatus in which a three-color image is formed by a solid-state image sensor having a solid-state image sensor for forming a green color image and a color coding filter for each of the red and blue pixels, or a three CCD type solid-state imaging apparatus in which the three-color image is formed by separate solid-state image sensors.
A technique for improving the resolution in the above mentioned multi-CCD type solid-state image sensor known as pixel shifting of offsetting may be utilized, in which the solid-state image sensors for forming red and blue color images are offset with respect to the solid-state image sensor for forming a green color image by one half the spatial pixel sampling period. The use of the spatial offsetting technique allows high resolution, that is, beyond the limit of the number of pixels in the solid-state image sensor, to be obtained in the analog output of the multi-CCD type solid-state imaging apparatus.
Digital video tape recorders, used in a broadcasting station or the like, may utilize a standard employing the D1/D2 format. As a result, the color television camera is required to provide a digital interface for digital video related equipment which is compatible with such standards. In the standard for the digital interface for digital video related equipment, the sampling rate is set to approximately the sampling rate fs of the presently available solid-state image sensor.